forked from grpc/grpc-java
/
RingHashLoadBalancerTest.java
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RingHashLoadBalancerTest.java
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/*
* Copyright 2021 The gRPC Authors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package io.grpc.xds;
import static com.google.common.truth.Truth.assertThat;
import static io.grpc.ConnectivityState.CONNECTING;
import static io.grpc.ConnectivityState.IDLE;
import static io.grpc.ConnectivityState.READY;
import static io.grpc.ConnectivityState.SHUTDOWN;
import static io.grpc.ConnectivityState.TRANSIENT_FAILURE;
import static org.mockito.ArgumentMatchers.any;
import static org.mockito.ArgumentMatchers.eq;
import static org.mockito.Mockito.atLeastOnce;
import static org.mockito.Mockito.clearInvocations;
import static org.mockito.Mockito.doAnswer;
import static org.mockito.Mockito.mock;
import static org.mockito.Mockito.never;
import static org.mockito.Mockito.reset;
import static org.mockito.Mockito.times;
import static org.mockito.Mockito.verify;
import static org.mockito.Mockito.verifyNoMoreInteractions;
import static org.mockito.Mockito.when;
import com.google.common.collect.Iterables;
import io.grpc.Attributes;
import io.grpc.CallOptions;
import io.grpc.ConnectivityStateInfo;
import io.grpc.EquivalentAddressGroup;
import io.grpc.LoadBalancer.CreateSubchannelArgs;
import io.grpc.LoadBalancer.Helper;
import io.grpc.LoadBalancer.PickResult;
import io.grpc.LoadBalancer.PickSubchannelArgs;
import io.grpc.LoadBalancer.ResolvedAddresses;
import io.grpc.LoadBalancer.Subchannel;
import io.grpc.LoadBalancer.SubchannelPicker;
import io.grpc.LoadBalancer.SubchannelStateListener;
import io.grpc.Metadata;
import io.grpc.Status;
import io.grpc.Status.Code;
import io.grpc.SynchronizationContext;
import io.grpc.internal.PickSubchannelArgsImpl;
import io.grpc.testing.TestMethodDescriptors;
import io.grpc.xds.RingHashLoadBalancer.RingHashConfig;
import java.lang.Thread.UncaughtExceptionHandler;
import java.net.SocketAddress;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Deque;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import org.junit.After;
import org.junit.Before;
import org.junit.Rule;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.JUnit4;
import org.mockito.ArgumentCaptor;
import org.mockito.Captor;
import org.mockito.InOrder;
import org.mockito.Mock;
import org.mockito.Mockito;
import org.mockito.invocation.InvocationOnMock;
import org.mockito.junit.MockitoJUnit;
import org.mockito.junit.MockitoRule;
import org.mockito.stubbing.Answer;
/** Unit test for {@link io.grpc.LoadBalancer}. */
@RunWith(JUnit4.class)
public class RingHashLoadBalancerTest {
private static final String AUTHORITY = "foo.googleapis.com";
private static final Attributes.Key<String> CUSTOM_KEY = Attributes.Key.create("custom-key");
@Rule
public final MockitoRule mocks = MockitoJUnit.rule();
private final SynchronizationContext syncContext = new SynchronizationContext(
new UncaughtExceptionHandler() {
@Override
public void uncaughtException(Thread t, Throwable e) {
throw new AssertionError(e);
}
});
private final Map<List<EquivalentAddressGroup>, Subchannel> subchannels = new HashMap<>();
private final Map<Subchannel, SubchannelStateListener> subchannelStateListeners =
new HashMap<>();
private final Deque<Subchannel> connectionRequestedQueue = new ArrayDeque<>();
private final XxHash64 hashFunc = XxHash64.INSTANCE;
@Mock
private Helper helper;
@Captor
private ArgumentCaptor<SubchannelPicker> pickerCaptor;
private RingHashLoadBalancer loadBalancer;
@Before
public void setUp() {
when(helper.getAuthority()).thenReturn(AUTHORITY);
when(helper.getSynchronizationContext()).thenReturn(syncContext);
when(helper.createSubchannel(any(CreateSubchannelArgs.class))).thenAnswer(
new Answer<Subchannel>() {
@Override
public Subchannel answer(InvocationOnMock invocation) throws Throwable {
CreateSubchannelArgs args = (CreateSubchannelArgs) invocation.getArguments()[0];
final Subchannel subchannel = mock(Subchannel.class);
when(subchannel.getAllAddresses()).thenReturn(args.getAddresses());
when(subchannel.getAttributes()).thenReturn(args.getAttributes());
subchannels.put(args.getAddresses(), subchannel);
doAnswer(new Answer<Void>() {
@Override
public Void answer(InvocationOnMock invocation) throws Throwable {
subchannelStateListeners.put(
subchannel, (SubchannelStateListener) invocation.getArguments()[0]);
return null;
}
}).when(subchannel).start(any(SubchannelStateListener.class));
doAnswer(new Answer<Void>() {
@Override
public Void answer(InvocationOnMock invocation) throws Throwable {
connectionRequestedQueue.offer(subchannel);
return null;
}
}).when(subchannel).requestConnection();
return subchannel;
}
});
loadBalancer = new RingHashLoadBalancer(helper);
// Skip uninterested interactions.
verify(helper).getAuthority();
verify(helper).getSynchronizationContext();
}
@After
public void tearDown() {
loadBalancer.shutdown();
for (Subchannel subchannel : subchannels.values()) {
verify(subchannel).shutdown();
}
connectionRequestedQueue.clear();
}
@Test
public void subchannelLazyConnectUntilPicked() {
RingHashConfig config = new RingHashConfig(10, 100);
List<EquivalentAddressGroup> servers = createWeightedServerAddrs(1); // one server
loadBalancer.handleResolvedAddresses(
ResolvedAddresses.newBuilder()
.setAddresses(servers).setLoadBalancingPolicyConfig(config).build());
verify(helper).createSubchannel(any(CreateSubchannelArgs.class));
Subchannel subchannel = Iterables.getOnlyElement(subchannels.values());
verify(subchannel, never()).requestConnection();
verify(helper).updateBalancingState(eq(IDLE), pickerCaptor.capture());
// Picking subchannel triggers connection.
PickSubchannelArgs args = new PickSubchannelArgsImpl(
TestMethodDescriptors.voidMethod(), new Metadata(),
CallOptions.DEFAULT.withOption(XdsNameResolver.RPC_HASH_KEY, hashFunc.hashVoid()));
PickResult result = pickerCaptor.getValue().pickSubchannel(args);
assertThat(result.getStatus().isOk()).isTrue();
assertThat(result.getSubchannel()).isNull();
verify(subchannel).requestConnection();
deliverSubchannelState(subchannel, ConnectivityStateInfo.forNonError(CONNECTING));
verify(helper).updateBalancingState(eq(CONNECTING), any(SubchannelPicker.class));
// Subchannel becomes ready, triggers pick again.
deliverSubchannelState(subchannel, ConnectivityStateInfo.forNonError(READY));
verify(helper).updateBalancingState(eq(READY), pickerCaptor.capture());
result = pickerCaptor.getValue().pickSubchannel(args);
assertThat(result.getSubchannel()).isSameInstanceAs(subchannel);
verifyNoMoreInteractions(helper);
}
@Test
public void subchannelNotAutoReconnectAfterReenteringIdle() {
RingHashConfig config = new RingHashConfig(10, 100);
List<EquivalentAddressGroup> servers = createWeightedServerAddrs(1); // one server
loadBalancer.handleResolvedAddresses(
ResolvedAddresses.newBuilder()
.setAddresses(servers).setLoadBalancingPolicyConfig(config).build());
Subchannel subchannel = Iterables.getOnlyElement(subchannels.values());
InOrder inOrder = Mockito.inOrder(helper, subchannel);
inOrder.verify(helper).updateBalancingState(eq(IDLE), pickerCaptor.capture());
inOrder.verify(subchannel, never()).requestConnection();
// Picking subchannel triggers connection.
PickSubchannelArgs args = new PickSubchannelArgsImpl(
TestMethodDescriptors.voidMethod(), new Metadata(),
CallOptions.DEFAULT.withOption(XdsNameResolver.RPC_HASH_KEY, hashFunc.hashVoid()));
pickerCaptor.getValue().pickSubchannel(args);
inOrder.verify(subchannel).requestConnection();
deliverSubchannelState(subchannel, ConnectivityStateInfo.forNonError(READY));
inOrder.verify(helper).updateBalancingState(eq(READY), any(SubchannelPicker.class));
deliverSubchannelState(subchannel, ConnectivityStateInfo.forNonError(IDLE));
inOrder.verify(helper).updateBalancingState(eq(IDLE), pickerCaptor.capture());
inOrder.verify(subchannel, never()).requestConnection();
// Picking again triggers reconnection.
pickerCaptor.getValue().pickSubchannel(args);
inOrder.verify(subchannel).requestConnection();
}
@Test
public void aggregateSubchannelStates_connectingReadyIdleFailure() {
RingHashConfig config = new RingHashConfig(10, 100);
List<EquivalentAddressGroup> servers = createWeightedServerAddrs(1, 1);
InOrder inOrder = Mockito.inOrder(helper);
loadBalancer.handleResolvedAddresses(
ResolvedAddresses.newBuilder()
.setAddresses(servers).setLoadBalancingPolicyConfig(config).build());
inOrder.verify(helper, times(2)).createSubchannel(any(CreateSubchannelArgs.class));
inOrder.verify(helper).updateBalancingState(eq(IDLE), any(SubchannelPicker.class));
// one in CONNECTING, one in IDLE
deliverSubchannelState(
subchannels.get(Collections.singletonList(servers.get(0))),
ConnectivityStateInfo.forNonError(CONNECTING));
inOrder.verify(helper).updateBalancingState(eq(CONNECTING), any(SubchannelPicker.class));
verifyConnection(0);
// two in CONNECTING
deliverSubchannelState(
subchannels.get(Collections.singletonList(servers.get(1))),
ConnectivityStateInfo.forNonError(CONNECTING));
inOrder.verify(helper).updateBalancingState(eq(CONNECTING), any(SubchannelPicker.class));
verifyConnection(0);
// one in CONNECTING, one in READY
deliverSubchannelState(
subchannels.get(Collections.singletonList(servers.get(1))),
ConnectivityStateInfo.forNonError(READY));
inOrder.verify(helper).updateBalancingState(eq(READY), any(SubchannelPicker.class));
verifyConnection(0);
// one in TRANSIENT_FAILURE, one in READY
deliverSubchannelState(
subchannels.get(Collections.singletonList(servers.get(0))),
ConnectivityStateInfo.forTransientFailure(
Status.UNKNOWN.withDescription("unknown failure")));
inOrder.verify(helper).refreshNameResolution();
inOrder.verify(helper).updateBalancingState(eq(READY), any(SubchannelPicker.class));
verifyConnection(0);
// one in TRANSIENT_FAILURE, one in IDLE
deliverSubchannelState(
subchannels.get(Collections.singletonList(servers.get(1))),
ConnectivityStateInfo.forNonError(IDLE));
inOrder.verify(helper).refreshNameResolution();
inOrder.verify(helper).updateBalancingState(eq(CONNECTING), any(SubchannelPicker.class));
verifyConnection(1);
verifyNoMoreInteractions(helper);
}
private void verifyConnection(int times) {
for (int i = 0; i < times; i++) {
Subchannel connectOnce = connectionRequestedQueue.poll();
assertThat(connectOnce).isNotNull();
clearInvocations(connectOnce);
}
assertThat(connectionRequestedQueue.poll()).isNull();
}
@Test
public void aggregateSubchannelStates_twoOrMoreSubchannelsInTransientFailure() {
RingHashConfig config = new RingHashConfig(10, 100);
List<EquivalentAddressGroup> servers = createWeightedServerAddrs(1, 1, 1, 1);
InOrder inOrder = Mockito.inOrder(helper);
loadBalancer.handleResolvedAddresses(
ResolvedAddresses.newBuilder()
.setAddresses(servers).setLoadBalancingPolicyConfig(config).build());
inOrder.verify(helper, times(4)).createSubchannel(any(CreateSubchannelArgs.class));
inOrder.verify(helper).updateBalancingState(eq(IDLE), any(SubchannelPicker.class));
// one in TRANSIENT_FAILURE, three in IDLE
deliverSubchannelState(
subchannels.get(Collections.singletonList(servers.get(0))),
ConnectivityStateInfo.forTransientFailure(
Status.UNAVAILABLE.withDescription("not found")));
inOrder.verify(helper).refreshNameResolution();
inOrder.verify(helper).updateBalancingState(eq(CONNECTING), any(SubchannelPicker.class));
verifyConnection(1);
// two in TRANSIENT_FAILURE, two in IDLE
deliverSubchannelState(
subchannels.get(Collections.singletonList(servers.get(1))),
ConnectivityStateInfo.forTransientFailure(
Status.UNAVAILABLE.withDescription("also not found")));
inOrder.verify(helper).refreshNameResolution();
inOrder.verify(helper)
.updateBalancingState(eq(TRANSIENT_FAILURE), any(SubchannelPicker.class));
verifyConnection(1);
// two in TRANSIENT_FAILURE, one in CONNECTING, one in IDLE
// The overall state is dominated by the two in TRANSIENT_FAILURE.
deliverSubchannelState(
subchannels.get(Collections.singletonList(servers.get(2))),
ConnectivityStateInfo.forNonError(CONNECTING));
inOrder.verify(helper)
.updateBalancingState(eq(TRANSIENT_FAILURE), any(SubchannelPicker.class));
verifyConnection(1);
// three in TRANSIENT_FAILURE, one in CONNECTING
deliverSubchannelState(
subchannels.get(Collections.singletonList(servers.get(3))),
ConnectivityStateInfo.forTransientFailure(
Status.UNAVAILABLE.withDescription("connection lost")));
inOrder.verify(helper).refreshNameResolution();
inOrder.verify(helper)
.updateBalancingState(eq(TRANSIENT_FAILURE), any(SubchannelPicker.class));
verifyConnection(1);
// three in TRANSIENT_FAILURE, one in READY
deliverSubchannelState(
subchannels.get(Collections.singletonList(servers.get(2))),
ConnectivityStateInfo.forNonError(READY));
inOrder.verify(helper).updateBalancingState(eq(READY), any(SubchannelPicker.class));
verifyConnection(0);
verifyNoMoreInteractions(helper);
}
@Test
public void subchannelStayInTransientFailureUntilBecomeReady() {
RingHashConfig config = new RingHashConfig(10, 100);
List<EquivalentAddressGroup> servers = createWeightedServerAddrs(1, 1, 1);
loadBalancer.handleResolvedAddresses(
ResolvedAddresses.newBuilder()
.setAddresses(servers).setLoadBalancingPolicyConfig(config).build());
verify(helper, times(3)).createSubchannel(any(CreateSubchannelArgs.class));
verify(helper).updateBalancingState(eq(IDLE), any(SubchannelPicker.class));
reset(helper);
// Simulate picks have taken place and subchannels have requested connection.
for (Subchannel subchannel : subchannels.values()) {
deliverSubchannelState(subchannel, ConnectivityStateInfo.forTransientFailure(
Status.UNAUTHENTICATED.withDescription("Permission denied")));
}
verify(helper, times(3)).refreshNameResolution();
// Stays in IDLE when until there are two or more subchannels in TRANSIENT_FAILURE.
verify(helper).updateBalancingState(eq(CONNECTING), any(SubchannelPicker.class));
verify(helper, times(2))
.updateBalancingState(eq(TRANSIENT_FAILURE), any(SubchannelPicker.class));
verifyConnection(3);
verifyNoMoreInteractions(helper);
reset(helper);
// Simulate underlying subchannel auto reconnect after backoff.
for (Subchannel subchannel : subchannels.values()) {
deliverSubchannelState(subchannel, ConnectivityStateInfo.forNonError(CONNECTING));
}
verify(helper, times(3))
.updateBalancingState(eq(TRANSIENT_FAILURE), any(SubchannelPicker.class));
verifyConnection(3);
verifyNoMoreInteractions(helper);
// Simulate one subchannel enters READY.
deliverSubchannelState(
subchannels.values().iterator().next(), ConnectivityStateInfo.forNonError(READY));
verify(helper).updateBalancingState(eq(READY), any(SubchannelPicker.class));
}
@Test
public void updateConnectionIterator() {
RingHashConfig config = new RingHashConfig(10, 100);
List<EquivalentAddressGroup> servers = createWeightedServerAddrs(1, 1, 1);
InOrder inOrder = Mockito.inOrder(helper);
loadBalancer.handleResolvedAddresses(
ResolvedAddresses.newBuilder()
.setAddresses(servers).setLoadBalancingPolicyConfig(config).build());
verify(helper, times(3)).createSubchannel(any(CreateSubchannelArgs.class));
verify(helper).updateBalancingState(eq(IDLE), any(SubchannelPicker.class));
deliverSubchannelState(
subchannels.get(Collections.singletonList(servers.get(0))),
ConnectivityStateInfo.forTransientFailure(
Status.UNAVAILABLE.withDescription("connection lost")));
inOrder.verify(helper).refreshNameResolution();
inOrder.verify(helper)
.updateBalancingState(eq(CONNECTING), any(SubchannelPicker.class));
verifyConnection(1);
servers = createWeightedServerAddrs(1,1);
loadBalancer.handleResolvedAddresses(
ResolvedAddresses.newBuilder()
.setAddresses(servers).setLoadBalancingPolicyConfig(config).build());
inOrder.verify(helper)
.updateBalancingState(eq(CONNECTING), any(SubchannelPicker.class));
verifyConnection(1);
deliverSubchannelState(
subchannels.get(Collections.singletonList(servers.get(1))),
ConnectivityStateInfo.forTransientFailure(
Status.UNAVAILABLE.withDescription("connection lost")));
inOrder.verify(helper).refreshNameResolution();
inOrder.verify(helper)
.updateBalancingState(eq(TRANSIENT_FAILURE), any(SubchannelPicker.class));
verifyConnection(1);
deliverSubchannelState(
subchannels.get(Collections.singletonList(servers.get(0))),
ConnectivityStateInfo.forNonError(CONNECTING));
inOrder.verify(helper)
.updateBalancingState(eq(TRANSIENT_FAILURE), any(SubchannelPicker.class));
verifyConnection(1);
}
@Test
public void ignoreShutdownSubchannelStateChange() {
RingHashConfig config = new RingHashConfig(10, 100);
List<EquivalentAddressGroup> servers = createWeightedServerAddrs(1, 1, 1);
loadBalancer.handleResolvedAddresses(
ResolvedAddresses.newBuilder()
.setAddresses(servers).setLoadBalancingPolicyConfig(config).build());
verify(helper, times(3)).createSubchannel(any(CreateSubchannelArgs.class));
verify(helper).updateBalancingState(eq(IDLE), any(SubchannelPicker.class));
loadBalancer.shutdown();
for (Subchannel sc : subchannels.values()) {
verify(sc).shutdown();
// When the subchannel is being shut down, a SHUTDOWN connectivity state is delivered
// back to the subchannel state listener.
deliverSubchannelState(sc, ConnectivityStateInfo.forNonError(SHUTDOWN));
}
verifyNoMoreInteractions(helper);
}
@Test
public void deterministicPickWithHostsPartiallyRemoved() {
RingHashConfig config = new RingHashConfig(10, 100);
List<EquivalentAddressGroup> servers = createWeightedServerAddrs(1, 1, 1, 1, 1);
loadBalancer.handleResolvedAddresses(
ResolvedAddresses.newBuilder()
.setAddresses(servers).setLoadBalancingPolicyConfig(config).build());
InOrder inOrder = Mockito.inOrder(helper);
inOrder.verify(helper, times(5)).createSubchannel(any(CreateSubchannelArgs.class));
inOrder.verify(helper).updateBalancingState(eq(IDLE), any(SubchannelPicker.class));
// Bring all subchannels to READY so that next pick always succeeds.
for (Subchannel subchannel : subchannels.values()) {
deliverSubchannelState(subchannel, ConnectivityStateInfo.forNonError(READY));
inOrder.verify(helper).updateBalancingState(eq(READY), pickerCaptor.capture());
}
// Simulate rpc hash hits one ring entry exactly for server1.
long rpcHash = hashFunc.hashAsciiString("[FakeSocketAddress-server1]_0");
PickSubchannelArgs args = new PickSubchannelArgsImpl(
TestMethodDescriptors.voidMethod(), new Metadata(),
CallOptions.DEFAULT.withOption(XdsNameResolver.RPC_HASH_KEY, rpcHash));
pickerCaptor.getValue().pickSubchannel(args);
PickResult result = pickerCaptor.getValue().pickSubchannel(args);
Subchannel subchannel = result.getSubchannel();
assertThat(subchannel.getAddresses()).isEqualTo(servers.get(1));
List<EquivalentAddressGroup> updatedServers = new ArrayList<>();
for (EquivalentAddressGroup addr : servers.subList(0, 2)) { // only server0 and server1 left
Attributes attr = addr.getAttributes().toBuilder().set(CUSTOM_KEY, "custom value").build();
updatedServers.add(new EquivalentAddressGroup(addr.getAddresses(), attr));
}
loadBalancer.handleResolvedAddresses(
ResolvedAddresses.newBuilder()
.setAddresses(updatedServers).setLoadBalancingPolicyConfig(config).build());
verify(subchannels.get(Collections.singletonList(servers.get(0))))
.updateAddresses(Collections.singletonList(updatedServers.get(0)));
verify(subchannels.get(Collections.singletonList(servers.get(1))))
.updateAddresses(Collections.singletonList(updatedServers.get(1)));
inOrder.verify(helper).updateBalancingState(eq(READY), pickerCaptor.capture());
assertThat(pickerCaptor.getValue().pickSubchannel(args).getSubchannel())
.isSameInstanceAs(subchannel);
verifyNoMoreInteractions(helper);
}
@Test
public void deterministicPickWithNewHostsAdded() {
RingHashConfig config = new RingHashConfig(10, 100);
List<EquivalentAddressGroup> servers = createWeightedServerAddrs(1, 1); // server0 and server1
loadBalancer.handleResolvedAddresses(
ResolvedAddresses.newBuilder()
.setAddresses(servers).setLoadBalancingPolicyConfig(config).build());
InOrder inOrder = Mockito.inOrder(helper);
inOrder.verify(helper, times(2)).createSubchannel(any(CreateSubchannelArgs.class));
inOrder.verify(helper).updateBalancingState(eq(IDLE), pickerCaptor.capture());
// Bring all subchannels to READY so that next pick always succeeds.
for (Subchannel subchannel : subchannels.values()) {
deliverSubchannelState(subchannel, ConnectivityStateInfo.forNonError(READY));
inOrder.verify(helper).updateBalancingState(eq(READY), pickerCaptor.capture());
}
// Simulate rpc hash hits one ring entry exactly for server1.
long rpcHash = hashFunc.hashAsciiString("[FakeSocketAddress-server1]_0");
PickSubchannelArgs args = new PickSubchannelArgsImpl(
TestMethodDescriptors.voidMethod(), new Metadata(),
CallOptions.DEFAULT.withOption(XdsNameResolver.RPC_HASH_KEY, rpcHash));
pickerCaptor.getValue().pickSubchannel(args);
PickResult result = pickerCaptor.getValue().pickSubchannel(args);
Subchannel subchannel = result.getSubchannel();
assertThat(subchannel.getAddresses()).isEqualTo(servers.get(1));
servers = createWeightedServerAddrs(1, 1, 1, 1, 1); // server2, server3, server4 added
loadBalancer.handleResolvedAddresses(
ResolvedAddresses.newBuilder()
.setAddresses(servers).setLoadBalancingPolicyConfig(config).build());
inOrder.verify(helper, times(3)).createSubchannel(any(CreateSubchannelArgs.class));
inOrder.verify(helper).updateBalancingState(eq(READY), pickerCaptor.capture());
assertThat(pickerCaptor.getValue().pickSubchannel(args).getSubchannel())
.isSameInstanceAs(subchannel);
verifyNoMoreInteractions(helper);
}
@Test
public void skipFailingHosts_pickNextNonFailingHostInFirstTwoHosts() {
// Map each server address to exactly one ring entry.
RingHashConfig config = new RingHashConfig(3, 3);
List<EquivalentAddressGroup> servers = createWeightedServerAddrs(1, 1, 1);
loadBalancer.handleResolvedAddresses(
ResolvedAddresses.newBuilder()
.setAddresses(servers).setLoadBalancingPolicyConfig(config).build());
verify(helper, times(3)).createSubchannel(any(CreateSubchannelArgs.class));
verify(helper).updateBalancingState(eq(IDLE), any(SubchannelPicker.class)); // initial IDLE
reset(helper);
// ring:
// "[FakeSocketAddress-server1]_0"
// "[FakeSocketAddress-server0]_0"
// "[FakeSocketAddress-server2]_0"
long rpcHash = hashFunc.hashAsciiString("[FakeSocketAddress-server0]_0");
PickSubchannelArgs args = new PickSubchannelArgsImpl(
TestMethodDescriptors.voidMethod(), new Metadata(),
CallOptions.DEFAULT.withOption(XdsNameResolver.RPC_HASH_KEY, rpcHash));
// Bring down server0 to force trying server2.
deliverSubchannelState(
subchannels.get(Collections.singletonList(servers.get(0))),
ConnectivityStateInfo.forTransientFailure(
Status.UNAVAILABLE.withDescription("unreachable")));
verify(helper).updateBalancingState(eq(CONNECTING), pickerCaptor.capture());
verifyConnection(1);
PickResult result = pickerCaptor.getValue().pickSubchannel(args);
assertThat(result.getStatus().isOk()).isTrue();
assertThat(result.getSubchannel()).isNull(); // buffer request
verify(subchannels.get(Collections.singletonList(servers.get(2))))
.requestConnection(); // kick off connection to server2
verify(subchannels.get(Collections.singletonList(servers.get(1))), never())
.requestConnection(); // no excessive connection
reset(helper);
deliverSubchannelState(
subchannels.get(Collections.singletonList(servers.get(2))),
ConnectivityStateInfo.forNonError(CONNECTING));
verify(helper).updateBalancingState(eq(CONNECTING), pickerCaptor.capture());
result = pickerCaptor.getValue().pickSubchannel(args);
assertThat(result.getStatus().isOk()).isTrue();
assertThat(result.getSubchannel()).isNull(); // buffer request
deliverSubchannelState(
subchannels.get(Collections.singletonList(servers.get(2))),
ConnectivityStateInfo.forNonError(READY));
verify(helper).updateBalancingState(eq(READY), pickerCaptor.capture());
result = pickerCaptor.getValue().pickSubchannel(args);
assertThat(result.getStatus().isOk()).isTrue();
assertThat(result.getSubchannel().getAddresses()).isEqualTo(servers.get(2));
}
@Test
public void skipFailingHosts_firstTwoHostsFailed_pickNextFirstReady() {
// Map each server address to exactly one ring entry.
RingHashConfig config = new RingHashConfig(3, 3);
List<EquivalentAddressGroup> servers = createWeightedServerAddrs(1, 1, 1);
loadBalancer.handleResolvedAddresses(
ResolvedAddresses.newBuilder()
.setAddresses(servers).setLoadBalancingPolicyConfig(config).build());
verify(helper, times(3)).createSubchannel(any(CreateSubchannelArgs.class));
verify(helper).updateBalancingState(eq(IDLE), any(SubchannelPicker.class)); // initial IDLE
reset(helper);
// ring:
// "[FakeSocketAddress-server1]_0"
// "[FakeSocketAddress-server0]_0"
// "[FakeSocketAddress-server2]_0"
long rpcHash = hashFunc.hashAsciiString("[FakeSocketAddress-server0]_0");
PickSubchannelArgs args = new PickSubchannelArgsImpl(
TestMethodDescriptors.voidMethod(), new Metadata(),
CallOptions.DEFAULT.withOption(XdsNameResolver.RPC_HASH_KEY, rpcHash));
// Bring down server0 and server2 to force trying server1.
deliverSubchannelState(
subchannels.get(Collections.singletonList(servers.get(0))),
ConnectivityStateInfo.forTransientFailure(
Status.UNAVAILABLE.withDescription("unreachable")));
deliverSubchannelState(
subchannels.get(Collections.singletonList(servers.get(2))),
ConnectivityStateInfo.forTransientFailure(
Status.PERMISSION_DENIED.withDescription("permission denied")));
verify(helper).updateBalancingState(eq(TRANSIENT_FAILURE), pickerCaptor.capture());
verifyConnection(2); // LB attempts to recover by itself
PickResult result = pickerCaptor.getValue().pickSubchannel(args);
assertThat(result.getStatus().isOk()).isFalse(); // fail the RPC
assertThat(result.getStatus().getCode())
.isEqualTo(Code.UNAVAILABLE); // with error status for the original server hit by hash
assertThat(result.getStatus().getDescription()).isEqualTo("unreachable");
verify(subchannels.get(Collections.singletonList(servers.get(1))))
.requestConnection(); // kickoff connection to server3 (next first non-failing)
verify(subchannels.get(Collections.singletonList(servers.get(0)))).requestConnection();
verify(subchannels.get(Collections.singletonList(servers.get(2)))).requestConnection();
// Now connecting to server1.
deliverSubchannelState(
subchannels.get(Collections.singletonList(servers.get(1))),
ConnectivityStateInfo.forNonError(CONNECTING));
verify(helper, times(2)).updateBalancingState(eq(TRANSIENT_FAILURE), pickerCaptor.capture());
result = pickerCaptor.getValue().pickSubchannel(args);
assertThat(result.getStatus().isOk()).isFalse(); // fail the RPC
assertThat(result.getStatus().getCode())
.isEqualTo(Code.UNAVAILABLE); // with error status for the original server hit by hash
assertThat(result.getStatus().getDescription()).isEqualTo("unreachable");
// Simulate server1 becomes READY.
deliverSubchannelState(
subchannels.get(Collections.singletonList(servers.get(1))),
ConnectivityStateInfo.forNonError(READY));
verify(helper).updateBalancingState(eq(READY), pickerCaptor.capture());
result = pickerCaptor.getValue().pickSubchannel(args);
assertThat(result.getStatus().isOk()).isTrue(); // succeed
assertThat(result.getSubchannel().getAddresses()).isEqualTo(servers.get(1)); // with server1
}
@Test
public void allSubchannelsInTransientFailure() {
// Map each server address to exactly one ring entry.
RingHashConfig config = new RingHashConfig(3, 3);
List<EquivalentAddressGroup> servers = createWeightedServerAddrs(1, 1, 1);
loadBalancer.handleResolvedAddresses(
ResolvedAddresses.newBuilder()
.setAddresses(servers).setLoadBalancingPolicyConfig(config).build());
verify(helper, times(3)).createSubchannel(any(CreateSubchannelArgs.class));
verify(helper).updateBalancingState(eq(IDLE), any(SubchannelPicker.class));
// Bring all subchannels to TRANSIENT_FAILURE.
for (Subchannel subchannel : subchannels.values()) {
deliverSubchannelState(subchannel, ConnectivityStateInfo.forTransientFailure(
Status.UNAVAILABLE.withDescription(
subchannel.getAddresses().getAddresses() + " unreachable")));
}
verify(helper, atLeastOnce())
.updateBalancingState(eq(TRANSIENT_FAILURE), pickerCaptor.capture());
verifyConnection(3);
// Picking subchannel triggers connection. RPC hash hits server0.
PickSubchannelArgs args = new PickSubchannelArgsImpl(
TestMethodDescriptors.voidMethod(), new Metadata(),
CallOptions.DEFAULT.withOption(XdsNameResolver.RPC_HASH_KEY, hashFunc.hashVoid()));
PickResult result = pickerCaptor.getValue().pickSubchannel(args);
assertThat(result.getStatus().isOk()).isFalse();
assertThat(result.getStatus().getCode()).isEqualTo(Code.UNAVAILABLE);
assertThat(result.getStatus().getDescription())
.isEqualTo("[FakeSocketAddress-server0] unreachable");
verify(subchannels.get(Collections.singletonList(servers.get(0))))
.requestConnection();
verify(subchannels.get(Collections.singletonList(servers.get(1))))
.requestConnection();
verify(subchannels.get(Collections.singletonList(servers.get(2))))
.requestConnection();
}
@Test
public void firstSubchannelIdle() {
// Map each server address to exactly one ring entry.
RingHashConfig config = new RingHashConfig(3, 3);
List<EquivalentAddressGroup> servers = createWeightedServerAddrs(1, 1, 1);
loadBalancer.handleResolvedAddresses(
ResolvedAddresses.newBuilder()
.setAddresses(servers).setLoadBalancingPolicyConfig(config).build());
verify(helper, times(3)).createSubchannel(any(CreateSubchannelArgs.class));
verify(helper).updateBalancingState(eq(IDLE), any(SubchannelPicker.class));
deliverSubchannelState(subchannels.get(Collections.singletonList(servers.get(1))),
ConnectivityStateInfo.forTransientFailure(
Status.UNAVAILABLE.withDescription("unreachable")));
verify(helper).updateBalancingState(eq(CONNECTING), pickerCaptor.capture());
verifyConnection(1);
// Picking subchannel triggers connection. RPC hash hits server0.
PickSubchannelArgs args = new PickSubchannelArgsImpl(
TestMethodDescriptors.voidMethod(), new Metadata(),
CallOptions.DEFAULT.withOption(XdsNameResolver.RPC_HASH_KEY, hashFunc.hashVoid()));
PickResult result = pickerCaptor.getValue().pickSubchannel(args);
assertThat(result.getStatus().isOk()).isTrue();
verify(subchannels.get(Collections.singletonList(servers.get(0))))
.requestConnection();
verify(subchannels.get(Collections.singletonList(servers.get(1))), never())
.requestConnection();
verify(subchannels.get(Collections.singletonList(servers.get(2))), never())
.requestConnection();
}
@Test
public void firstSubchannelConnecting() {
// Map each server address to exactly one ring entry.
RingHashConfig config = new RingHashConfig(3, 3);
List<EquivalentAddressGroup> servers = createWeightedServerAddrs(1, 1, 1);
loadBalancer.handleResolvedAddresses(
ResolvedAddresses.newBuilder()
.setAddresses(servers).setLoadBalancingPolicyConfig(config).build());
verify(helper, times(3)).createSubchannel(any(CreateSubchannelArgs.class));
verify(helper).updateBalancingState(eq(IDLE), any(SubchannelPicker.class));
deliverSubchannelState(subchannels.get(Collections.singletonList(servers.get(0))),
ConnectivityStateInfo.forNonError(CONNECTING));
deliverSubchannelState(subchannels.get(Collections.singletonList(servers.get(1))),
ConnectivityStateInfo.forNonError(CONNECTING));
verify(helper, times(2)).updateBalancingState(eq(CONNECTING), pickerCaptor.capture());
// Picking subchannel triggers connection.
PickSubchannelArgs args = new PickSubchannelArgsImpl(
TestMethodDescriptors.voidMethod(), new Metadata(),
CallOptions.DEFAULT.withOption(XdsNameResolver.RPC_HASH_KEY, hashFunc.hashVoid()));
PickResult result = pickerCaptor.getValue().pickSubchannel(args);
assertThat(result.getStatus().isOk()).isTrue();
verify(subchannels.get(Collections.singletonList(servers.get(0))), never())
.requestConnection();
verify(subchannels.get(Collections.singletonList(servers.get(1))), never())
.requestConnection();
verify(subchannels.get(Collections.singletonList(servers.get(2))), never())
.requestConnection();
}
@Test
public void firstSubchannelFailure() {
// Map each server address to exactly one ring entry.
RingHashConfig config = new RingHashConfig(3, 3);
List<EquivalentAddressGroup> servers = createWeightedServerAddrs(1, 1, 1);
loadBalancer.handleResolvedAddresses(
ResolvedAddresses.newBuilder()
.setAddresses(servers).setLoadBalancingPolicyConfig(config).build());
verify(helper, times(3)).createSubchannel(any(CreateSubchannelArgs.class));
verify(helper).updateBalancingState(eq(IDLE), any(SubchannelPicker.class));
// ring:
// "[FakeSocketAddress-server1]_0"
// "[FakeSocketAddress-server0]_0"
// "[FakeSocketAddress-server2]_0"
deliverSubchannelState(subchannels.get(Collections.singletonList(servers.get(0))),
ConnectivityStateInfo.forTransientFailure(
Status.UNAVAILABLE.withDescription("unreachable")));
verify(helper).updateBalancingState(eq(CONNECTING), pickerCaptor.capture());
verifyConnection(1);
// Picking subchannel triggers connection.
PickSubchannelArgs args = new PickSubchannelArgsImpl(
TestMethodDescriptors.voidMethod(), new Metadata(),
CallOptions.DEFAULT.withOption(XdsNameResolver.RPC_HASH_KEY, hashFunc.hashVoid()));
PickResult result = pickerCaptor.getValue().pickSubchannel(args);
assertThat(result.getStatus().isOk()).isTrue();
verify(subchannels.get(Collections.singletonList(servers.get(0))))
.requestConnection();
verify(subchannels.get(Collections.singletonList(servers.get(2))))
.requestConnection();
verify(subchannels.get(Collections.singletonList(servers.get(1))), never())
.requestConnection();
}
@Test
public void secondSubchannelConnecting() {
// Map each server address to exactly one ring entry.
RingHashConfig config = new RingHashConfig(3, 3);
List<EquivalentAddressGroup> servers = createWeightedServerAddrs(1, 1, 1);
loadBalancer.handleResolvedAddresses(
ResolvedAddresses.newBuilder()
.setAddresses(servers).setLoadBalancingPolicyConfig(config).build());
verify(helper, times(3)).createSubchannel(any(CreateSubchannelArgs.class));
verify(helper).updateBalancingState(eq(IDLE), any(SubchannelPicker.class));
// ring:
// "[FakeSocketAddress-server1]_0"
// "[FakeSocketAddress-server0]_0"
// "[FakeSocketAddress-server2]_0"
Subchannel firstSubchannel = subchannels.get(Collections.singletonList(servers.get(0)));
deliverSubchannelState(firstSubchannel,
ConnectivityStateInfo.forTransientFailure(Status.UNAVAILABLE.withDescription(
firstSubchannel.getAddresses().getAddresses() + "unreachable")));
deliverSubchannelState(subchannels.get(Collections.singletonList(servers.get(2))),
ConnectivityStateInfo.forNonError(CONNECTING));
verify(helper, times(2)).updateBalancingState(eq(CONNECTING), pickerCaptor.capture());
verifyConnection(1);
// Picking subchannel triggers connection.
PickSubchannelArgs args = new PickSubchannelArgsImpl(
TestMethodDescriptors.voidMethod(), new Metadata(),
CallOptions.DEFAULT.withOption(XdsNameResolver.RPC_HASH_KEY, hashFunc.hashVoid()));
PickResult result = pickerCaptor.getValue().pickSubchannel(args);
assertThat(result.getStatus().isOk()).isTrue();
verify(subchannels.get(Collections.singletonList(servers.get(0))))
.requestConnection();
verify(subchannels.get(Collections.singletonList(servers.get(2))), never())
.requestConnection();
verify(subchannels.get(Collections.singletonList(servers.get(1))), never())
.requestConnection();
}
@Test
public void secondSubchannelFailure() {
// Map each server address to exactly one ring entry.
RingHashConfig config = new RingHashConfig(3, 3);
List<EquivalentAddressGroup> servers = createWeightedServerAddrs(1, 1, 1);
loadBalancer.handleResolvedAddresses(
ResolvedAddresses.newBuilder()
.setAddresses(servers).setLoadBalancingPolicyConfig(config).build());
verify(helper, times(3)).createSubchannel(any(CreateSubchannelArgs.class));
verify(helper).updateBalancingState(eq(IDLE), any(SubchannelPicker.class));
// ring:
// "[FakeSocketAddress-server1]_0"
// "[FakeSocketAddress-server0]_0"
// "[FakeSocketAddress-server2]_0"
Subchannel firstSubchannel = subchannels.get(Collections.singletonList(servers.get(0)));
deliverSubchannelState(firstSubchannel,
ConnectivityStateInfo.forTransientFailure(Status.UNAVAILABLE.withDescription(
firstSubchannel.getAddresses().getAddresses() + " unreachable")));
deliverSubchannelState(subchannels.get(Collections.singletonList(servers.get(2))),
ConnectivityStateInfo.forTransientFailure(
Status.UNAVAILABLE.withDescription("unreachable")));
verify(helper).updateBalancingState(eq(TRANSIENT_FAILURE), pickerCaptor.capture());
verifyConnection(2);
// Picking subchannel triggers connection.
PickSubchannelArgs args = new PickSubchannelArgsImpl(
TestMethodDescriptors.voidMethod(), new Metadata(),
CallOptions.DEFAULT.withOption(XdsNameResolver.RPC_HASH_KEY, hashFunc.hashVoid()));
PickResult result = pickerCaptor.getValue().pickSubchannel(args);
assertThat(result.getStatus().isOk()).isFalse();
assertThat(result.getStatus().getCode()).isEqualTo(Code.UNAVAILABLE);
assertThat(result.getStatus().getDescription())
.isEqualTo("[FakeSocketAddress-server0] unreachable");
verify(subchannels.get(Collections.singletonList(servers.get(0))))
.requestConnection();
verify(subchannels.get(Collections.singletonList(servers.get(2))))
.requestConnection();
verify(subchannels.get(Collections.singletonList(servers.get(1))))
.requestConnection();
}
@Test
public void thirdSubchannelConnecting() {
// Map each server address to exactly one ring entry.
RingHashConfig config = new RingHashConfig(3, 3);
List<EquivalentAddressGroup> servers = createWeightedServerAddrs(1, 1, 1);
loadBalancer.handleResolvedAddresses(
ResolvedAddresses.newBuilder()
.setAddresses(servers).setLoadBalancingPolicyConfig(config).build());
verify(helper, times(3)).createSubchannel(any(CreateSubchannelArgs.class));
verify(helper).updateBalancingState(eq(IDLE), any(SubchannelPicker.class));
// ring:
// "[FakeSocketAddress-server1]_0"
// "[FakeSocketAddress-server0]_0"
// "[FakeSocketAddress-server2]_0"
Subchannel firstSubchannel = subchannels.get(Collections.singletonList(servers.get(0)));
deliverSubchannelState(firstSubchannel,
ConnectivityStateInfo.forTransientFailure(Status.UNAVAILABLE.withDescription(
firstSubchannel.getAddresses().getAddresses() + " unreachable")));
deliverSubchannelState(subchannels.get(Collections.singletonList(servers.get(2))),
ConnectivityStateInfo.forTransientFailure(
Status.UNAVAILABLE.withDescription("unreachable")));
deliverSubchannelState(subchannels.get(Collections.singletonList(servers.get(1))),
ConnectivityStateInfo.forNonError(CONNECTING));
verify(helper, times(2)).updateBalancingState(eq(TRANSIENT_FAILURE), pickerCaptor.capture());
verifyConnection(3);
// Picking subchannel triggers connection.
PickSubchannelArgs args = new PickSubchannelArgsImpl(
TestMethodDescriptors.voidMethod(), new Metadata(),
CallOptions.DEFAULT.withOption(XdsNameResolver.RPC_HASH_KEY, hashFunc.hashVoid()));
PickResult result = pickerCaptor.getValue().pickSubchannel(args);
assertThat(result.getStatus().isOk()).isFalse();
assertThat(result.getStatus().getCode()).isEqualTo(Code.UNAVAILABLE);
assertThat(result.getStatus().getDescription())
.isEqualTo("[FakeSocketAddress-server0] unreachable");
verify(subchannels.get(Collections.singletonList(servers.get(0))))
.requestConnection();
verify(subchannels.get(Collections.singletonList(servers.get(2))))
.requestConnection();
verify(subchannels.get(Collections.singletonList(servers.get(1))), never())
.requestConnection();
}
@Test
public void stickyTransientFailure() {
// Map each server address to exactly one ring entry.
RingHashConfig config = new RingHashConfig(3, 3);
List<EquivalentAddressGroup> servers = createWeightedServerAddrs(1, 1, 1);
loadBalancer.handleResolvedAddresses(
ResolvedAddresses.newBuilder()
.setAddresses(servers).setLoadBalancingPolicyConfig(config).build());
verify(helper, times(3)).createSubchannel(any(CreateSubchannelArgs.class));
verify(helper).updateBalancingState(eq(IDLE), any(SubchannelPicker.class));
// Bring one subchannel to TRANSIENT_FAILURE.
Subchannel firstSubchannel = subchannels.get(Collections.singletonList(servers.get(0)));
deliverSubchannelState(firstSubchannel,
ConnectivityStateInfo.forTransientFailure(
Status.UNAVAILABLE.withDescription(
firstSubchannel.getAddresses().getAddresses() + " unreachable")));
verify(helper).updateBalancingState(eq(CONNECTING), any());
verifyConnection(1);
deliverSubchannelState(firstSubchannel, ConnectivityStateInfo.forNonError(IDLE));
verify(helper, times(2)).updateBalancingState(eq(CONNECTING), pickerCaptor.capture());
verifyConnection(1);
// Picking subchannel triggers connection. RPC hash hits server0.
PickSubchannelArgs args = new PickSubchannelArgsImpl(
TestMethodDescriptors.voidMethod(), new Metadata(),
CallOptions.DEFAULT.withOption(XdsNameResolver.RPC_HASH_KEY, hashFunc.hashVoid()));
PickResult result = pickerCaptor.getValue().pickSubchannel(args);
assertThat(result.getStatus().isOk()).isTrue();
verify(subchannels.get(Collections.singletonList(servers.get(0)))).requestConnection();
verify(subchannels.get(Collections.singletonList(servers.get(2)))).requestConnection();
verify(subchannels.get(Collections.singletonList(servers.get(1))), never())
.requestConnection();
}
@Test
public void hostSelectionProportionalToWeights() {
RingHashConfig config = new RingHashConfig(10000, 100000); // large ring
List<EquivalentAddressGroup> servers = createWeightedServerAddrs(1, 10, 100); // 1:10:100
loadBalancer.handleResolvedAddresses(
ResolvedAddresses.newBuilder()
.setAddresses(servers).setLoadBalancingPolicyConfig(config).build());
verify(helper, times(3)).createSubchannel(any(CreateSubchannelArgs.class));
verify(helper).updateBalancingState(eq(IDLE), any(SubchannelPicker.class));
// Bring all subchannels to READY.
Map<EquivalentAddressGroup, Integer> pickCounts = new HashMap<>();
for (Subchannel subchannel : subchannels.values()) {
deliverSubchannelState(subchannel, ConnectivityStateInfo.forNonError(READY));
pickCounts.put(subchannel.getAddresses(), 0);
}
verify(helper, times(3)).updateBalancingState(eq(READY), pickerCaptor.capture());
SubchannelPicker picker = pickerCaptor.getValue();
for (int i = 0; i < 10000; i++) {
long hash = hashFunc.hashInt(i);
PickSubchannelArgs args = new PickSubchannelArgsImpl(
TestMethodDescriptors.voidMethod(), new Metadata(),
CallOptions.DEFAULT.withOption(XdsNameResolver.RPC_HASH_KEY, hash));
Subchannel pickedSubchannel = picker.pickSubchannel(args).getSubchannel();
EquivalentAddressGroup addr = pickedSubchannel.getAddresses();
pickCounts.put(addr, pickCounts.get(addr) + 1);
}
// Actual distribution: server0 = 104, server1 = 808, server2 = 9088
double ratio01 = (double) pickCounts.get(servers.get(0)) / pickCounts.get(servers.get(1));
double ratio12 = (double) pickCounts.get(servers.get(1)) / pickCounts.get(servers.get(2));
assertThat(ratio01).isWithin(0.03).of((double) 1 / 10);
assertThat(ratio12).isWithin(0.03).of((double) 10 / 100);
}
@Test
public void hostSelectionProportionalToRepeatedAddressCount() {
RingHashConfig config = new RingHashConfig(10000, 100000);
List<EquivalentAddressGroup> servers = createRepeatedServerAddrs(1, 10, 100); // 1:10:100
loadBalancer.handleResolvedAddresses(
ResolvedAddresses.newBuilder()
.setAddresses(servers).setLoadBalancingPolicyConfig(config).build());
verify(helper, times(3)).createSubchannel(any(CreateSubchannelArgs.class));
verify(helper).updateBalancingState(eq(IDLE), any(SubchannelPicker.class));
// Bring all subchannels to READY.
Map<EquivalentAddressGroup, Integer> pickCounts = new HashMap<>();
for (Subchannel subchannel : subchannels.values()) {
deliverSubchannelState(subchannel, ConnectivityStateInfo.forNonError(READY));
pickCounts.put(subchannel.getAddresses(), 0);
}
verify(helper, times(3)).updateBalancingState(eq(READY), pickerCaptor.capture());
SubchannelPicker picker = pickerCaptor.getValue();
for (int i = 0; i < 10000; i++) {
long hash = hashFunc.hashInt(i);
PickSubchannelArgs args = new PickSubchannelArgsImpl(
TestMethodDescriptors.voidMethod(), new Metadata(),